Exoskeleton with Admittance Control

1. An exoskeleton system comprising: a passive arm support having at least one joint to articulate the arm support; a forearm cuff attached to or integral to the arm support; at least one sensor attached between the forearm cuff and the passive arm support, the sensor being adapted to detect applied force, or torque from a user; a plurality of motors mounted at each joint in the arm support to control position and orientation of the forearm cuff, and to create a passive-motorized hybrid arm support, the plurality of motors enabling motorized control of the arm support; a plurality of motor horns attached on the plurality of motors that allows motion translation of a shaft to a physical body outside the motors so that the motor horns directly drive the at least one joint for eliminating backlash or play that propagate motor error and position error; an antigravity force mechanism that applies a constant upward and vertical force equal and opposite to a force of gravity acting on a user's arm; a controller coupled to the plurality of motors and the at least one sensor, an admittance control loop to motorize the passive support, wherein the controller is programmed with the admittance control loop; an admittance control and an impedance control to control the position and orientation of the passive arm support based on applied forces and torques from the user; the admittance control is applied to a fully motorized three degree of freedom (3 DOF) system, a motor position conversion unit coupled with the admittance control for receiving inverse kinematics and boundary conditions from the admittance control; an exoskeleton for support and direction of the user's arm through movement based on a residual strength of the user, and processed through the admittance control loop, wherein the passive support uses the admittance control and the impedance control for user exoskeleton interaction; wherein the antigravity force mechanism further includes a virtual mass, and a damping or a damping coefficient required to keep the exoskeleton stable; wherein, the user is able to be controlling motion of the forearm cuff while only being opposed by inertia of the virtual mass and the damping; a time delay for the admittance control loop that is 10 ms or less to ensure the user exoskeleton interaction, wherein the impedance control decreases the time delay between a user interface and actual motion of the exoskeleton; a virtual point mass for mapping the user's applied force to motion of the exoskeleton wherein the virtual point mass, friction, and inertia of the exoskeleton are minimized as compared to not using the virtual point mass for users with Duchenne muscular dystrophy (DMD) to operate the exoskeleton despite user diminished muscle strength; the virtual point mass is set at 0.5 kg and the damping coefficient is set at 25 N*sec/m.; a wheelchair, a table, or a desk at which the user is seated for mounting the exoskeleton thereon; wherein, a joint angle is converted to a motor position and used to control an angle of each motor to translate and orient the forearm cuff and the user's arm to a desired position and orientation for each iteration of the control loop based on an applied force and a torque; and wherein, the user is intuitively controlling motion of the forearm cuff while only being opposed by the inertia of the 0.5 kg virtual mass and the damping coefficient required to keep the system stable.

2. The exoskeleton of claim 1 , wherein the admittance control receives from the sensor movement, force, and torque information and the admittance control determines a desired end effector, position, and orientation for transmission to the impedance control that controls the motors of the exoskeleton.

3. The exoskeleton of claim 1 , further including a direct drive system that is used in combination with the motor horns.

4. The exoskeleton of claim 1 , wherein the sensor is a force sensor, and the force sensor is adapted to detect user input in a vertical axis.

5. The exoskeleton of claim 1 , wherein the sensor is a force-torque sensor, and the force-torque sensor is adapted to detect and measure movement in a “x” axis, a “y” axis and a “z” axis, and a first and a second angular change in pitch and yaw, wherein the sensor also measure a third angular change in a roll direction.

6. The exoskeleton of claim 1 wherein the antigravity force mechanism that further includes the damping coefficient and the virtual mass is dynamic and programmable for adjustment without changing components to compensate for changes in a medical condition of the user.

7. The exoskeleton of claim 1 , wherein the antigravity force mechanism is selected from a group consisting of a motor controlled by a positional-integral-derivative controller (PID), a servomotor mechanism, a pneumatic drive mechanism, a dampener, a dashpot, and any combination thereof.

8. The exoskeleton of claim 1 , wherein the admittance control has input of force from the residual strength of the user and output of position; and wherein the impedance control utilizes the user's arm position as input and the output is torque.

9. The exoskeleton of claim 1 , wherein the virtual mass and the damping coefficient is dynamic and programmable to adjust without changing components of the exoskeleton to compensate for changes in user medical condition.

10. A method of using an exoskeleton system, comprising: providing an exoskeleton system according to claim 1 ; wherein the passive arm support is retrofitted with the force sensor and the motor; and implementing the admittance control loop within the motor.

11. An exoskeleton system comprising: a passive support having at least one joint to articulate the passive support; a forearm cuff attached to or integral to the support; at least one sensor attached between the forearm cuff and the passive support, the sensor being adapted to detect applied force, or torque from a user; a plurality of motors mounted at each joint in the passive support to control position and orientation of the forearm cuff, and to create a passive-motorized hybrid support, the plurality of motors enabling motorized control of the passive support; an antigravity force mechanism that applies a constant upward and vertical force equal and opposite to a force of gravity acting on a user's arm, a controller coupled to the plurality of motors and the at least one sensor, an admittance control loop to motorize the passive support, wherein the controller is programmed with the admittance control loop; an admittance control and an impedance control to control the position and orientation of the passive support based on applied forces and torques from the user; the admittance control is applied to a fully motorized three degree of freedom (3 DOF) system, a motor position conversion unit coupled with the admittance control for receiving inverse kinematics and boundary conditions from the admittance control; an exoskeleton for support and direction of an arm of the user through movement based on a residual strength of the user, and processed through the admittance control loop, wherein the passive support uses the admittance control and the impedance control for user exoskeleton interaction; wherein the antigravity force mechanism further includes a virtual mass, and a damping or a damping coefficient required to keep the exoskeleton stable; wherein, the user is able to be controlling motion of the forearm cuff while only being opposed by inertia of the virtual mass and the damping; a time delay for the admittance control loop that is 10 ms or less to ensure the user exoskeleton interaction, wherein the impedance control decreases the time delay between a user interface and actual motion of the exoskeleton; a virtual point mass for mapping the user's applied force to motion of the exoskeleton wherein the virtual point mass, friction, and inertia of the exoskeleton are minimized as compared to not using the virtual point mass for users with Duchenne muscular dystrophy (DMD) to operate the exoskeleton despite user diminished muscle strength; the virtual point mass is set at 0.5 kg and the damping coefficient is set at 25 N*sec/m.; a wheelchair, a table, or a desk at which the user is seated for mounting the exoskeleton thereon; wherein, a joint angle is converted to a motor position and used to control an angle of each motor to translate and orient the forearm cuff and the user's arm to a desired position and orientation for each iteration of the control loop based on an applied force and a torque; and wherein, the user is intuitively controlling motion of the forearm cuff while only being opposed by the inertia of the 0.5 kg virtual mass and the damping coefficient required to keep the system stable.

12. The exoskeleton system of claim 11 , wherein the passive support is configured to be attached to a limb of the user.

13. The exoskeleton system of claim 12 , wherein the limb includes: an arm, a forearm, a leg, an ankle, a finger, a foot, a toe, a hand, a neck, a head, a wrist, and any combination thereof.

14. The exoskeleton system of claim 11 , wherein the passive support is configured to be attached to a limb of the user, and the admittance control loop detects a force applied by the limb of the user and converts the force into positional data to position the passive support and the limb of the user.

15. The exoskeleton system of claim 14 , wherein the force is detected in z direction.

16. The exoskeleton system of claim 11 , wherein acceleration, position, and corresponding motor positions are calculated based on a user's real-time applied force every 0.01 seconds, and wherein every iteration of the admittance control loop operates at 100 Hz for the user to control a position of a limb of the user in space while only opposed by inertia of a smaller point of mass than applied to the passive support.

17. A method of using an exoskeleton system, comprising: providing an exoskeleton system having: a passive arm support having at least one joint to articulate the arm support; a forearm cuff attached to or integral to the arm support; at least one sensor attached between the forearm cuff and the passive arm support, the sensor being adapted to detect applied force, or torque from a user; a plurality of motors mounted at each joint in the arm support to control position and orientation of the forearm cuff, and to create a passive-motorized hybrid arm support, the plurality of motors enabling motorized control of the arm support; an antigravity force mechanism that applies a constant upward and vertical force equal and opposite to a force of gravity acting on a user's arm; a controller coupled to the plurality of motors and the at least one sensor, an admittance control loop to motorize the passive support, wherein the controller is programmed with the admittance control loop; an admittance control and an impedance control to control the position and orientation of the passive arm support based on applied forces and torques from the user; the admittance control is applied to a fully motorized three degree of freedom (3 DOF) system, a motor position conversion unit coupled with the admittance control for receiving inverse kinematics and boundary conditions from the admittance control; an exoskeleton for support and direction of the user's arm through movement based on a residual strength of the user, and processed through the admittance control loop, wherein the passive support uses the admittance control and the impedance control for user exoskeleton interaction; wherein the antigravity force mechanism further includes a virtual mass, and a damping or a damping coefficient required to keep the exoskeleton stable; wherein, the user is able to be controlling motion of the forearm cuff while only being opposed by inertia of the virtual mass and the damping; a time delay for the admittance control loop that is 10 ms or less to ensure the user exoskeleton interaction, wherein the impedance control decreases the time delay between a user interface and actual motion of the exoskeleton; a virtual point mass for mapping the user's applied force to motion of the exoskeleton wherein the virtual point mass, friction, and inertia of the exoskeleton are minimized as compared to not using the virtual point mass for users with Duchenne muscular dystrophy (DMD) to operate the exoskeleton despite user diminished muscle strength; the virtual point mass is set at 0.5 kg and the damping coefficient is set at 25 N*sec/m.; a wheelchair, a table, or a desk at which the user is seated for mounting the exoskeleton thereon; wherein, a joint angle is converted to a motor position and used to control an angle of each motor to translate and orient the forearm cuff and the user's arm to a desired position and orientation for each iteration of the control loop based on an applied force and a torque; and wherein, the user is intuitively controlling motion of the forearm cuff while only being opposed by the inertia of the 0.5 kg virtual mass and the damping coefficient required to keep the system stable.

18. The method of claim 17 , wherein the exoskeleton is used for rehabilitative purposes.